Migrants are seen aboard a boat tethered to a Thai navy vessel, in waters near Koh Lipe island, May 16, 2015. A boat crammed with migrants was towed out to sea by the Thai navy and then held up by Malaysian vessels on Saturday, the latest round of "maritime ping-pong" by Asian states determined not to let asylum seekers come ashore. The United Nations has called on countries around the Andaman Sea not to push back the thousands of desperate Bangladeshis and Rohingya Muslims from Myanmar now stranded in wooden boats, and to rescue them instead. REUTERS/Olivia Harris (THAILAND)